Mobile communication system, radio base station apparatus, operation control method therefor and program

Abstract

There is provided a radio base station apparatus capable of self-recovery from an AICH abnormal state or notification to maintenance personnel. An RACH preamble detection circuit detects an RACH preamble from an inputted delay profile, and outputs detection information (detection position and reception power) on the detected RACH preamble, to an AICH abnormality determination section. The AICH abnormality determination section determines whether an AICH abnormal state has been caused in which a mobile station retransmits an RACH preamble in spite of a base station having already detected the RACH preamble, based on the detection information. If the AICH abnormal state has been caused, then an AICH / alarm control section controls the transmit power for the AICH or outputs an alarm signal.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a mobile communication system, a radio base station apparatus, an operation control method therefor, and a program, and particularly to an improvement of a mobile communication system that a mobile station transmits an RACH (random access channel) preamble to a base station prior to transmitting an RACH message to the base station, and in response to detection of the RACH preamble, the base station transmits an AICH (acquisition indicator channel) to the mobile station.[0003]2. Description of the Related Art[0004]Recently, the interference-resistant spread spectrum communication method has attracted a lot of attention as one of communication methods applicable to mobile communication systems. In a radio communication system using the spread spectrum communication method, after digitized voce data or image data is modulated with a digital modulation method such as the PSK and FSK modulati...

AI Technical Summary

Benefits of technology

[0020]The object of the present invention is to provide a mobile communication system, a radio base station apparatus, an operation control method therefor and a program, capable of self-recovery from an AICH abnormal state or notification of an AICH abnormal state to maintenance personnel.

[0033]In this way, the determination means is adapted to determine whether or not a mobile station can receive an AICH with the use of detection information on an RACH preamble, thereby enabling self-recovery from an AICH abnormal state or notification of the abnormal state to maintenance personnel.

Problems solved by technology

That is, for a mobile station located near the border of a cell of the radio base station apparatus, for example, it is difficult to receive an AICH.

In such a case, if there are more mobile stations in the center of the cell than near the border, the phenomenon that the radio base station apparatus cannot receive an RACH message does not appear obviously, and therefore it is difficult for maintenance personnel to find it.

To the user who cannot send an RACH message, however, such condition seems to be a state in which he cannot start communication or a call for a long time (no service state). which will significantly damage his reliability on the communication service.

As described above, there is a problem that even if a mobile station cannot detect an AICH because of bad AICH receiving conditions, recovery from the AICH abnormal state cannot be performed until RACH messages cannot be sent so frequently that maintenance personnel notice the AICH abnormal state and change the setting for the AICH transmit power.

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